more numbers definitely, more energy. >> as the workload increases, so does the stress. >> do you ever dream about work? >> i have dreamted about work, yes. i dreamted about picking items. >> reporter: sometimes items are too far apart to walk. this is amazon's biggest fulfillment center. to fwif you an idea it is the equivalent of 28 football fields which explains why some employees need try troiks to get around. >> with this holiday season expected to be the biggest one yet they have brought in 50,000 extra workers. >> an on-line operation that depends on the human touch to fulfill holiday wishes. nbc news, phoenix, arizona. >> when we return, a rockin' celebration. >> the rolling stones are flying high tonight as they celebrated 50 years as a band with 20,000 of their closest fans. the group kicked off the anniversary tour where it all began in london. the 69-year-old mick jagger and band mates thrilled the audience for more than 2 1/2 hours with hits like "brown sugar" and "jumping jack flash" they will be in new york 0 in december with a show on pay per view. >> we made it. happy